As legend has it, in 2737 B.C. Emperor Sheng Nong was boiling water under a tea tree, when leaves fell into his pot. He drank the brew and became enamored of its flavor. Fueled by a passion for medical herbs, he wrote of the extensive health benefits of tea. Modern science has substantiated many of the early claims regarding the health effects of tea. Among its many benefits, green tea can contribute to weight loss.

Active Ingredients

Green tea.
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Green tea contains chemicals called catechins, a type of polyphenol that promotes the health of the tea plant. Catechins are powerful antioxidents that neutralize the damaging effect of free radicals, rogue compounds that scavenge other cells for electrons. The catechins in tea, as well as other active ingredients, such as caffeine and the polyphenol theanine, seem to help humans as well. The polyphenols in green tea are associated with a lower risk for certain types of cancer, Parkinson’s disease, heart attacks and several neurological disorders, the Psychology Today website reports. They also promote weight loss and enhance fat metabolism, according to the University of Maryland Medical Center.

Boost Your Metabolism

Caffeine and catechins in green tea appear to increase metabolism and cause weight loss. The type of catechin in green tea, epigallocatechin gallate, or EGCG, increases the production of heat, increasing the number of calories you burn in every activity, from breathing to running. A 12-week study published in the February 2008 issue of “Physiology & Behavior” found that participants who drank green tea daily lost 7.3 lbs. more weight than non-tea drinkers who had identical diets. The study authors concluded that green tea increased participants’ energy expenditure and fat metabolism.

Slow Your Digestion

Catechins in green tea assist in the regulation of glucose by slowing the release of digested sugar into your bloodstream. This prevents spikes in glucose and dampens insulin response, slowing the transformation of blood glucose into fat. Green tea enhances insulin sensitivity, muting over-production of insulin and stabilizing blood sugar, so you have fuel readily available for your brain and body. Having stable blood sugar also staunches your appetite and reduces food cravings.

Inhibit Fat Absorption

Catechins in tea decrease the absorption of glucose into fat cells. Consumption of high amounts of catechins significantly affects fat distribution in moderately overweight people, a 2010 study in “Obesity” reports. Four groups drank tea that differed in the amount of catechins. Participants who drank the most catechins had significant improvements in body fat, body mass, waist size and weight.

Decrease Your Appetite

The caffeine in green tea can suppress your appetite, but the catechins might be especially potent. A study from the University of Chicago, described at UC Hospitals, found that rats injected with EGCG ate as much as 60 percent less food. A June 2009 study published in “Clinical Nutrition” found that green tea suppressed hunger and increased satiety in humans, especially when participants were experiencing a calorie deficit. You can drink tea at any time and potentially experience weight-loss benefits, but drinking green tea during meals may provide additional benefits. Green tea has no calories, but it fills your stomach, sating your appetite just as you are poised to eat. It slows release of sugar from digested food, but does so only if you drink it while you are eating.

Green tea is no magic bullet. To lose weight, create a calorie deficit by eating fewer calories. Green tea can assist your efforts. Drink it any time of day, but make it your beverage of choice during meals to give your weight-loss efforts a boost.